Here is my latest project, a monoblock audio power amp SE design using the typical and easy to find tubes! I am making it with parts used in past projects, though the box and chassis base plate is a new layout design. The OT is a Hammond 125ESE and sounds pretty good for the price. Its really neat to have these around, tube amps add a warmth to the music and its very enjoyable! I have one in my work shop and have one in my living room too, though this amp is going to replace that one.

I am working on the board layout now and will post that probably next week sometime.

I have made some changes to the schematic and have decided to go with only one stage or 1/2 of a 12AX7. I decided to do this just so I could try and sharpen some of my math skills, and load line theory. My goal is to calculate the best values for Rg, Ra(Rp), Rl, Ck and Co based on my voltage. Right now without any load my power rail is seeing 412V. I think this should drop when everything is hooked up, can anyone calculate these values? (OHM's LAW) As I learn this concept better I will be documenting it here. Maybe we will get some input from someone who already knows this better.

Here is what I have so far

Great work man! It looks very simple

Would be also a great project for me when I finish my other guitar stuff...
but the time it's very hard at the moment...


Thomas

Thanks!

Yeah, audio amps are for the most part simple and are really neat to have around. I buy used stereo tuners from the 70's just so I can run my own tube amps. You can also plug CD's, mp3, into them too. Nothing like kicking back in a dimly lit room listing to them and watching the tubes glow!

Yeah you said it very good! I don't know why but that's also one point that makes tubes so special for me "you see the gear working" it's not as a modern HiFi thing with 2 LED's which is buzzing in the background

I think we can understand each other

Thomas

Yup thats half the enjoyment!

Well, I finally got around to testing and she sounds very good! But I am going to tweak some values just a tad. Once I do that and finalize it I will post all the values and actual operating voltages. Basically I am going to change the 5k's in the power rail to around 1k then the OT then 5k, and remove one since Rp (preamp) is only 100V right now and the cathode seems to like the 1.5k range, though this might change.....I should have some more updates soon.

Well, its amazing but by changing two power rail resistors I gained 200V at Rp and its a good thing I reduced theses values too since they were drawing too many watts. I new this right off the bat since as soon as I through the power switch I could smell a slight burning smell, and I knew we had too much resistance going on. With the new values all is good and no burning smell at all.

Some Pictures: